Highly-refractory material and process for making it.



' UNITED STATESTATENT oFrIcE;

AUGUST IBFAFF, OF FREIBEBG, GERMANY,

HIGHLY- REFRACTORY MATERIAL AND PROCESS FOR MAKING IT. I

No Drawing";

To all whom it may concern Be it known that I, Dr. AUGUs'r PFAFF', subject of the King of Prussia, residin at 24 Frauensteinerstrasse, .Freiberg, .in. ony, Germany, have invented certain new and useful Improvements in Highly-Refractory Material and Process for Making It,"

I I I am aware that it is old to make highly refractory vessels from zirconia, and that it is equally old to employ'carborundum in the reparation of surfaces designed to be sub- ]ected to high temperatures. Vessels made from zirconia have proved to be of little value, as zirconia will, especially if em ployed in apparatus subjected to frequent variations in temperature, become 'cracked and brittle and will loose its mechanical coherence. On the other hand vessels consisting of carborundum show the disadvantage of not resisting the oxidizing influence of the air at high temperatures, the carbon gradually burning out and the melting point of the vessels bein thereby lowered to the melting point of sil ca.

In contradistinction to these materials'the articles made of .a mixture of carborundum and zirconiahave an absolute tough and homogeneous body of great density, a reaction between zirconia and carborundum apparently taking'place during the burning.

' ,This presumption is corroborated by the fact that these vessels on being burnt show a considerable shrinkage. The vessels made according tothe presentinvention will covered during the burning and 'more so during use with a more or less glazing-like layer, and this layer or coating seems to pro-n tect the interlor of the body against oxidation. All kinds -of articles can be manna faiztu'red cm the mixture aforesaidRQJ is equally a apted for the manufacture of mufiles for ceramic purposes, of crucibles, for

the lining of metallurgical furnaces and.

vSpecification of Letters Patent. Application filed March 24, 1915. Serial No. 16,820. a

Patented Nov. 2, 1915.

The constituents of the mixture are preferabl y employed in about equal parts. If it is desired to obtain the maximum of refractorlness, the sillco'n-carbid should be' employed in the form of a powder coarser in grain than the zirconia. 4 v

The highly refractory qualities of the new material make it. adapted also for the manufacture of electric resistances for use in such cases where it is imperative that the resistances shall be'eificacious also at high temperatures.-

The zirconia proper may also be replaced by the oxids of zirconium found in 'the trade; further additions may be made to the mass provided that they do not depress the melting point... g i

I claim:, 1. The process for making highly refrac tory articles which consists in mlxing zirconia and'carborundum, bring in the mixture into shape and burning t e shaped article.

- 2. The process for making; highly refractoryarticles which consists ,in mixing zirconia and carborundum, the particl {of carborundum being coarser, than tho e of the zirconia, bringing the mixture into shape and burning the shaped article. I

3. As. a new article of manufacture, a

highly refractory material consisting of a burnt mixture of zirconia and carborundum.-

4. .As a new article of manufacture, a highly refractory material consisting of a burnt mixture of about equal parts of. zirconia and carborundum.

5. As a new artlcle of manufacture, a.

highly refractory material consisting of a mixture .of zirconia andcarborundum, the

carborundum being coarser in grain than f 95 6. As a new artlcle of manufacture, a, hlghly refractory vessel conslsting of a burnt the zirconia. r

mixture of zirconla and carborundum.

- 7. As a new article of manufacture, a

highly refractoryl article consisting of a burnt mixture of zirconia and carborundum. In testimony whereof Iaflix my signature in presence of two'witnesses;

' DR- AUGUST PFAFF.

Witnesses:

WERNER HOFMANN, BERTOLD A. BRAUN; 

